Coupling radio frequency amplifier



y 14, 1929- A. s. BLATTERMAN 1,713,462

COUPLING RADIO FREQUENCY AMPLIFIER Original Filed June 13. 1922 IN VEN TOR /2950mm AME) Patented 7 May 14, 1929.

UNITED STATES 1,713,462 PATENT, OFFICE.

ALBERT S. BLATTERMAN, OF ASBURY PARK, NEW JERSEY, ASSIGNOR, BY MESNE AS- SIG'NMENTS, TO B. M. C. PATENT COM PORATION OF NEW JERSEY.

PANY, OF TREN'ION, NEW JERSEY, .A. COR- COUPLIN G RADIO FREQUENCY AMPLIFIER.

Application filed June 13, 1922, Serial N0..567,964. Renewed December 3, 1828.

winding the coils on said coupling reac'toror transformer. Heretofore it has been considered necessary to wind these coils very carefully with a view to obtamlng high efficiency and uniformity in operation in the production of large numbers for commercial use. A prima facie requirement in the construction of coupling reaction coils or transformers in a radio frequency amplifier employin g three-electrode vacuum tubes, is that the self-capacity of the said coils shall be kept low and as invariable as possible among a large number of similar units, andexpensive machinery and great care which has heretofore been used and exercised in the winding of said coils have been employed to meet these requirements.

I have discovered that the generally accepted idea on this subject is greatly exaggerated and that it is unnecessary to utilize the uniform and carefully constructed Windings that have heretofore beenemployed.

In forming the Winding according to this invention, I place the required number of turns in the core slot in a haphazard or random manner. The usual method of winding coils in even layers with successive turns regularly adjacent to one another is purposely avoided, and the greater the departure from regularity in winding, the better, since a purpose of this random winding is to reduce the self-capacity of the coil. Previous conceptions regarding such construction hold that lack of uniformity in the operation of the transformer and GXCGSSlVBSGlf-CEIPHCltY of the windings will result by the method described, and although such windings have been elsewhere employed in the art, they have been avoided as undesirable in radio frequency amoperation.

In the accompanying drawings:

Figure 1 is a diagramof a radio frequency amplifier embodying the invention,

Figure 2 shows the form of core and relation of windings, and v Figure 3 shows a modification for additional windings.

In Fig. 1 is indicated diagrammatically an amplifier of the type comprising my invention. Herein the circuit LC represents the input circuit to the amplifier in which the radio frequency voltage to be amplified originates. Such circuit is connected conventionally on the one hand to the grid electrode G of the vacuum tube 1; and on the other hand to the filament electrode F of the said vacuum tube 1. The plate electrode P of the vacuum tube 1 is connected conventionally to a reaction coil herein shown as a transformer T comprising a primary winding WV and a secondary winding V This transformer is designed to be especially effective and eflicient for amplification at radio frequencies and comprises a type of coupling means referred to in this invention. The plate electrode P of vacuum tube 1 is connected to one end of the primary of the said coupling transformer T and the other end of the primary WV is connected to a battery B and thence to the filament electrode F of the vacuum tube 1. The secondary winding of the coupling transformer or reaction coil T is connected either to the grid and filament electrodes of a second threeelectrode amplifier vacuum tube, as in the case of a multi-stage amplifier, or else to a suitable detector. In Fig. 1 is shown, for the sake of simplicity, the latter connection in which the secondary winding 7 of the coupling transformer T is connected on the one hand to the grid electrode G, of the three-electrode vacuum tube detector 2, and on the other hand to the filament electrode F of the said detector tube.

In Fig. 2 is shown an approved construction which I employ in a radio frequency amplifier transformer to be used in combina tion with three-electrode Vacuum tubesfor radio frequency amplification. The windlngs are formed in two narrow slots, S and S cut in a core of insulating material B. These slots are required to be Very narrow. For example-I have built numerous trans formers comprising this construction in which the slots are from to in width. It is desirable to restrict the width of the slot to a maximum of approximately and the capacity. 7 2O narrower the slot the better. In Fig. 2 the primary winding of the transformer is placed in one of the slots and the secondary 'winding in the otherslot, interchangeably and wound'irregularly to reduce self for proper functioning ofthe transformer exceeds the number which it is possible to wind in a single slot, or in two slots, one for the primary and one for the secondary,

then I employ a longer core, in which are out several similar narrow slots and the entire winding is distributed serially in the several slots. This construction is shown on Fig. 3, and 1s required 111 preference to w1nd1n g all of the turns'in a single wide slot because'bymy It the number of turns required construction the self-capacity of the finished winding is restricted to a low value.

While I have described in detail a' type of 7' construction comprising adjacent slots whose planes are parallel with one'another, other constructions, such for instance as single or multiple slot-s or grooves or self supporting windings and with primary and secondary" windings in the same slot or slots but wound one witnin the other, will be obvious to those skilled in the art, and do not depart from the being wound in'sections, the sections of one C011 being arranged 1n alternate relation with th sections of the other coil.

Signed at'New York, in the county of New York and State of New York, this 9th day of JuneA. D. 1922. r

. ALBERT S. BLATTERMAN. 

